Island



s'ra'rns PATENT OFFICE.

ROGER WILLIE-MS, OI PROVIDENCE, BHQDE ISLAND, ASSIGNGB '10 NITBOGEbI' PRODUCTS COMPANY, OF PROVIDENCE, RHODE ISLAND, A COBPOMTIONOI' RHODE ISLAND.

PROCESS OF AND MEANS FOR FIXING ATMOSPHERIC NITBOGER.

No Drawing.

To all whom it may concern: v Beit known that 1, Room: Wnmms, a citizen of the United States, residing at Providence, in the county of Providence and State of Rhode Island, have invented certain new and useful Improvements in Processes of and Means for 'Fixin Atmospheric Nitrogen, of which the fol owing-is a specification.

This invention relates to a process of and means for fixing atmospheric nitrogen and more especially to an improvement in or upon the process disclosedin the patent .to

John E. Bucher, No. 1,120,682, dated Dec. 15, 1914; the resentinventio'n having for one of its ob ects the effectuation of said Buche'r process in such manner as to increase the eflicacy thereof, both as regards the con version of carbonate of sodium, or the like,

vto cyanid, and also as regards the mechanical feeding of the preferably briqueted charge through the cyani-zing retort.

Another object of my invention is to produce a composition of matter. in briqueted form, which shall be more resistant to dis 'ruption and fracture, when cold, and more resistant to deformation and disintegration of its briqueted structure when under operative temperature and pressure conditions to which it must be subjected when in use; while at the same time in substantially no way impairing the efliciencv of the briquets for the formation of cyanid therein,but, on the contrary, actually improving them for this latter purpose.

vThese and other objects will be hereinafter referred to, and the novel combinations of steps in the process and ofelements in the briquet structure, will be more particularly pointed out in the claims appended hereto.

As I am aware of certain modifications and changes which may be effected herein,

without departing from the spirit of my invention, I desire to be limited only by the scope of said claims. broadly interpreted in the light of my disclosure.

As described in detail in said Bucher patent, the preferred mode of efiectuation of his said process is by reparing relatively small briquets of reactlve material, which includes iron, finely divided-or some equivalent catalytic material, 6. g. chro- Specification of Letters 1 mm. P t t 2 1919 Application filed October 28, 1917. Serial No. 198,711.

mium, manganese, nickel or cobalt,very intimately mixed with carbon and a substance such as sodium carbonate which acts not alone as a binder for .the briquets; but

also as a source of the metal which constitutes the base of the cyanid or other cyanogen compound to be formed. These briquets may be fed into a suitable retort and after being preheated, descend by gravity, or are otherwise moved into a heat zone where free nltrogen is caused to react upon the briqueted material toconvert a conslderable I ployed; but aside from the likelihood of in uring the catalyzer,-since the sodium carbonate or its equivalent, constitutes the binder for the briquets, it is highly undesirable to so elevate the temperature of the entire reactive mass, at any one time, as to excessively volatilize this binder. This, of course, is due to the fact that the briquet structure must be reasonably preserved in order to afford the requisite passages or ducts for the passage of the nitrogen through the mass and the elimination from the pores of said mass of the carbon monoxid formed during the course of the reaction; and also to prevent the charge from sticking in the retort.

With briquets formed as described in said patent to Bucher, however, I have discovered that there is a tendency for them to become over-plastic and, indeed at times in consequence thereof to thus cut oil more or less of the requisite nitrogen supply and even to choke the retorts, especially when operatin at a temperature well up above 1000 C. e. g. 1090 C.); the binder then being excessively liquefied and thereafter volatil-'L1 ized. If now this liquid were converted to a rather thick paste, so to speak, by the presence. therein of an excee ingly finely divided and preferably highly porous, irre larly surfaced material, this excessive u' idity and volatilization of melted portions carbonate as well.

of the sodium carbonate binder would be in part overcome. The difficulty was, however, to find such a substance, which would not be instrumental in introducing into the reactive mass impurities which the novel em loyment by said Bucher, of the sodium car onate itself as the preferably sole binder for the briquets, avoided.

Peculiarly, such a substance as most admirably meets the requirements, is actually evolved during the course of the operation as described in said patent; but was used merely to augment the supply of carbon in the briquets after they had already been formed and had been introduced into the furnace; I refer to the carbon deposited in the pores of and upon the briquets, from the conversion of the carbon-monoxid produced bv the reaction (su plemented by additional GO, if desired, in the manner described in said Bucher patent) into carbondioxid' in a zone or region in the retort or hopper, where the temperature of said carbon-monoxid was lowered sufficiently to permit of the conversion of much of said monoxid to the dioxid.

This carbon, as is stated in said patent, is ash-free and is for this and other reasons particularly well suited to the cyanid forming operation; the briquets upon which t is deposited or in the pores of which it is formed, dropping by gravity into. the heat zone, where after being cyanized, they are cooled and preferably then removed from the retort, to be treated to win the cyanid therefrom.

This operation, as formerly conducted, involved the lixiviation of the cyanized briquets with water, which dissolved out the cyanid and also, unfortunately, the sodium The bri u'ets hence became converted to a black slu ge from which the iron segregated, while, of course the greater part of the carbonate was removed therefrom in solution, to be recovered by subsequent treatment. The sludge which was largely carbon, was dried and of course caked into masses and lumps which were subsequently ground up and again mixed with iron and sodium carbonate, preparatory to being re-briqueted.

N ow it so happens that the carbon which is deposited in the pores of the briquets by the conversion of CO to 00,, as above described, is usually by no means wholly consumed in the subsequent cyan-id forming operation; but by the just described lixiviation and other treatment of the briquets, this material is practically lost to the process in so far as its peculiarly finely divided and hence reactive condition is concerned.

When, however,instead of lixiviating the cyanized briquets with water,-they are extracted with, liquid ammonia, this substance dissolves with 8 the alkali metal le, all traces of moisture during the extracting operation.

As, b the use of this solvent, the briquets are no onger converted to sludge,the exceedingly finely divided condition of the precipitated carbon is not impaired and itis merely necess to conserve it, preferably as far as prwctica le, 'durin the removal of the leached and thoroug y dry briquets from the leaching or extracting apparatus, and thereafter during the subsequent breaking up of the briquets preparatory to adding freshcarbonate and carbon to the material prior to the re-briqueting operation.

it may also observe that by operating in this fashion, the segregation of the pulverulent catalyzer, e. 9. iron or its equivalent, is

avoided; which materially reduces the time and cost of pre aring the intimate mixture of carbon, cata yzer and carbonate or the like, required for the cyanizing step or op-. eration a If care be not observed, however, and; the leaching or extracting apparatus is opened and the charge is dropped therefrom, especially when out of doors or in abuilding the doors and windows of which are open for any reason,then much of this very fine carbon .dust will be blown away or float ofi in the air and be completely lost to the process.

i I hence prefer to conduct all such steps in a fashion to conserve this' valuable substance; hoods or the like being used ina .less and free from silicates, sulfur and other deleterious impurities, which more or lesscontaminate the product (cyanid).

briquets conveniently or practicably be made solely of this ashfree carbon, the condition would be ideal. However, it has not yet been proven commercially practicable so to do; although I am at present at work upon this problem. On the other hand coke obtained from coal, such as has hitherto been used m the process, is always impure Could the entire supply of carbon in the thraiclte coke) up to seven or eight per cent.

or more.

' Other sources of available carbon tried, were correspondingly subject to this objection, which has proven rather a serious one, not because the presence of ash materially interferes with the cyanizing operation; but because it makes the final product impure. I have, however, also succeeded in practically overcoming this difficulty, by the use of what is known as petroleum coke,a product obtained by coking down heavy mineral 0ils,and when this coke is finely pulverized, it more nearly resembles gaseousreaction precipitated carbon such as that above described, than any other of which I am aware, which is commercially practicable. Its content of ash, if of reasonably good quality, ranges from less than onequarter of one per cent. to at times one and one-half per cent.; the average being perhaps, one per cent. The crushed particles thereof, further, seem to be finer and more adapted to the purpose in question than those of similarly treated ordinary coke or the like.

Hence, when carbon is added to the briquet material, I prefer to use the combi nation of finely pulverized petroleum coke, and as much of the precipitated carbon, or its equivalent, as is available. The. briquets are preferably prepared from a very intimate mixture of, say, equal parts of catalyst, carbon and reactive binder; the catalyst being pulverized manganese, iron, or other equivalent catalytic material; the carbon comprising finely crushed, high-grade, petroleum coke and all available precipitated carbon, produced as aforesaid; and the binder being preferably an alkali metal compound such as the carbonate, hydrate or oxid of sodium, or a mixture of these, in which mixture the carbonate preferably principally predominates.

The said intimate mixture is then slightly moistened; care being taken to add but substantially just suflicient water (either as liquid or in the form of steam) to enable the binding material to become effective as such, and not to unduly mush-up or cake the exceedingly fine carbon particles If, too, more water is added than is necessary, then some of the catalyst, especially if iron is used as the catalytic material,is apt to become partly oxidized, and while the subsequent cyanid forming operation will quickly reduce this oxid to metal; still, heat and carbon are consumed in so doing and the effectiveness of the catalyst, until reduced, is impaired.

The mass is then briqueted by pressure in suitable .apparatus, and after it has been slowly and thoroughly dried, it is available for use in the retort.

- Obviously, also, the carbonate or the like may be fused to cause it to become effective as a binder when the material is briqueted;

instead of forming the briquets by means of water, as above described. The first method is preferred, however, and, when but little water is thus used, this can be very readily driven off in the drying operation.

I do not as yet know, with certainty, just why the presence of the precipitated carbon and crushed petroleum coke in the binder increases the rigidity and resistance to crushing or rupture of the briquets, when cold,as compared to briquets prepared in the same manner but with ground coke (from coal) instead of the preferred carbonaceous material; and it may be that my theory, aforesaid, regarding the action of the precipitated carbon in connection with the partly molten binder, when the briquets are being cyanized, is incorrect. Be that as it may, however, the briquets prepared in accordance with my disclosure herein, are better able to resist fracture when cool or comparatively cool, and deformation or mashing up when in the heat'zone; while they feed through the retort much more readily,the tendency to stick in or choke the retort being markedly reduced. I may here state also, that the briquets are handled, mechanically or otherwise, even more when cold than when hot.

The efliciency of this important nitrogen fixation process is therefore considerably enhanced by the herein described improvement; and as I am aware'that other carbonaceous material in an extremely finely divided and rough or porous surfaced condition is available for use in the process, I do not desire to be limited solely to crushed petroleum-coke and the carbon precipitated during the conversion of carbon monoxid to carbon dioxid; although these materials are much preferred.

To this end, in certain of the appended claims such expressions as substantially pure carbon as produced in and deposited from gaseous material, are intended to cover the preferred carbon precipitated from carbon monoxid, as aforesaid, and also the carbon deposited in the fines which carry off the combustion products resulting from the production of sodium carbonate, and the like; carbon obtained from I the dissociation of partial decomposition of methane or other hydro-carbons; etc.

In general, carbon so produced or liberated by chemical reaction in gaseous materials, and when not excessively contaminated by impurities, is particularly available for use in the process on account not alone of its ultra-finely divided condition; but, further, on account of the rough orirregular and peculiarly porous surfaces of itspart1- cles. On the other hand, ordinary coke,

obtained from coal, normally has not only a high ash content, but further is so reslstant are relatively smooth and comparatively non-porous; certainly as compared to carbon dues. a

I am of the opinion also, that there 1s another relationship between this irregularly surfaced ultra-finely divided carbon and the treatment with water, of the mixture to be briqueted; in that if it be subjected to too much water, the exceedingly minute pores in the surfaces of the carbon particles tend, to become choked up. When, however, but

just sufiicient water is employed, as above described, it is probable that when this is? evaporated ofi' after briqueting, the carbon particles, while being knit or bound securely together, nevertheless have more or less open pores in their surfaces and,as they are substantially in contact with each other,- the given briquet comprising them, is pro. vided with a relatively complete system of tiny ducts or conduits for the passage of nitrogen theretbrough and the emergence of the cyanid-reaction-retarding carbon monoxid therefrom.

For a number of reasons, therefore, the importance of eliminating water as a means for removing the cyanid from cyanized briquets,'where the solid residues are to be again. incorporated in briquets, for return to the process,-will be appreciated. 1 make no'claim herein, however, to liquid ammonia, per 86, as a leaching agent, other than as this solvent co-acts with my preferred source of carbon for the cyanid forming operation, to enable the preservation and conservation of such carbon, in the manner described.

Finally, I desire to point out that while in the preferred mode of efl'ectuating the process I prefer to use an alkali metal compound, such, for example, as sodium carbonate, as the source of the base of the cyanogen compound to be formed, in certain of its aspects, my invention is not to be regarded as being limited to these, as I am aware that the nitrogen-fixing reaction may be efi'ectuated by the use of, for example, compounds of the earthralkalimetals, such as barium carbonate; and further that'the mixture of reactive material (carbon, catalyst and carbonate or the like) may have as its entire content of carbon, if deslred, such ultra-finely divided material as the precipitated carbon, aforesaid.

precipitated from gaseous reaction resi-- argest I have this in 'view because of a process which I have developed for-producing this substance. outside of the briquet mass disposed in the relatively cool zone above the heat or cyanid-forming reaction zone in the nitrogen fixing operation,'and I anticipate being able to render said process, thus in view, not-'merely'practicable on a small scale but in a commercially practicable way.

There are, however, certain advantages to be gained from using a mixture of such carbon with, preferably,'ptroleum coke powbri uets comprising catalytic material in fine y divided condition, carbon and a substance whichv constitutes both the source of the metallic base of said cyanogen compound and a binder for said briqu'ts,-the improvement which consists in incorporatingdirectly into the binder of and during the operation of forming said briquets, as a source of carbon for the'nitrogen-fixing reaction, carbonaceous material which comprises substantially pure fiocculent carbon as produced in and deposited from gaseous material.

2. In a process for fixing nitrogen in the form of a metal cyanogen compound, in which free nitrogen is caused to react upon briquets comprising catalytic material in finely divided condition, carbon and a substance which constitutes both the source of.v

the metallic base of said cyanogen compound and a binder forsaidbriquets,-theimprovement which consists in incorporating directly into the binder of and during the'operation of forming said briquets, as a source of carbon for the nitrogen-fixing reaction, carbonaceous material which comprises carbon particles, in an ultra-finely divided state, obtained from the conversion of carbon monoxid to carbon dioxid.

'3. In a process for fixing nitrogen in the form of a metal cyanogen compound, in which free mtrogen is caused to react upon 'bnquets comprising catalytic material in finely divided condition, carbon and a sub-- stance which constitutes both the source of the metallic base of said cyanogen compound and a binder for said briquets',-the improvement which consists in incorporating directly into the binder of and during which consists in mixing with said catathe operation of forming said briquets, as a source of carbon for the nitrogen-fixing reaction, carbonaceous material which comprises carbon particles, in an ultra-finely d1- vided state obtained from a gaseous reaction in which said carbon particles are thrown out of and tend to separate from the gaseous' reaction residues, so removing said cyanogen compound from said briquets, af-

ter its formation as aforesaid. as to leave such of said carbonaceous materia1 as remains unchanged b the cyanidform1ng reaction,-in substantially said ultra-finely d1- vided state, conservin such residual carbonaceous material an returni it to the process incorporated in fresh brlquets 4. In a process for fixing mtro n in the formof almetal cyanogen compoun m which free nitrogen is caused to react uponbriquets comprising catalytic material in finely divided condition, carbon and a substance which constitutes both the source of the metallic base of said cyanogen compound and a binder for said briquets,--the improvement which consists in incorporating directly into the binder of and during the operation of forming said briquets, as a source of carbon for the nitrogen-fixing reaction, carbonaceous material which comprises carbon particles, in an ultra-finely divided state, obtained from a gaseous reaction in which said carbon particles are thrown out of and tend to separate from the gaseous reaction residues, removing said cyanogen compound from 'said briquets, after its formation as aforesaid, by leaching sald briquets with liquid ammonia, so as to leave such of said carbonaceous material as remains unchanged by the cyanid forming reaction, in substantially said ultra-finely divided state, conserving such residual carbonaceous material and returning it to the process incorporated in fresh briquets.

5. In the manufacture of briquets for use in the process which involves reacting with free nitrogen upon material in the form of briquets which comprise catalytic metal in finely divided condition, carbon and a reactive binding material,-the improvement which consists in mixing with said catalytic metal and binding material, petroleum coke in finely divided condition and substantially ash-free carbon obtained by converting carbon monoxid to carbon dioxid, treating. the resulting mixture with substantially the minimum quantity of water necessary to enable it to be effectually briquetted, forming it into briquets, and driving off the water by heat.

'6. In the manufacture of briquets for use in the process which involves reacting with free nitrogen upon material in the form of briquets which comprise catalytic metal in finely divided condition, carbon and a reactive binding material,the improvement Iytic metal and binding material, substantially ash-free carbon obtained by converting ,carbon monoxid tocarbon dioxid, treating the resulting mixture with substantially the minimum uantity of water necessa to enable it to effectually briqueted, orming it into briquets, and driving off the water by heat. I a

7. In'the manufacture of briquets for use in the process which involves reacting with free nitrogen upon material in the form of bri nets which'com rise catalytic metal in fine y divided condition, carbon and areactive binding material,--the im rovement which consists in mixing with sai catalytic metal and binding material, substantially ure carbon as produced in and deposited rom gaseous material, treating the resulting mixture with substantially the minimum quantity of water necessary to enable it to be efi'ectually briqueted, forming it into briquets, and driving off the water by heat.

8. The process of fixing nitrogen which comprises reacting with free nitrogen upon a briqueted mixture of catalytic metal, substantiall ash-free carbon and the carbonate of an a ali metal, to form an alkali metal cyanogen compound, cooling the non-gaseous products of said reaction while preventi access of moisture thereto, extracting sai cyanogen compound b liquid ammonia from which substantially a l moisture is excluded, conserving the residue of said carbon and incorporating the same in fresh briquets for return to the process.

9. The process of fixing nitrogen which comprises reacting with free nitrogen upon an intimate mixture of catalytic material, finely crushed petroleum coke and an oxygen compound of an alkali metal capable of reacting with the substances aforesaid to form the cyanid of said alkali metal, cooling the non-gaseous products of said reaction while preventing access of moisture thereto, extracting said cyanogen compound by liquid ammonia; from which substantially all moisture is excluded, and conserving the residue of said carbon for return to the process.

10. The process of fixing nitrogen which comprises reacting with free nitrogen upon an intimate mixture of catalytic material, finely crushed petroleum coke and an oxygen compound of an alkali metal capable of reacting with the substances aforesaid to form the cyanid of said alkali metal, cooling the non-gaseous products of said reaction while preventing access of moisture thereto, and extracting said cyano en compound by liquid ammonia from w ich substantially al moisture is excluded.

11. The process of fixing nitrogen which comprises reacting with free nitrogen upon an intimate mixture of catalytic material, finely crushed petroleum coke and an oxygen compound of an alkali metal capable of reacting with the substances aforesald to form the cyanid of said alkali metal.

12. The step in an improved process for fixing nitrogen, which comprises forming a mixture of petroleum coke, sodium carbonate and catalytic material capable, when said mixture is heated to reacting temperature in the presence of free nitrogen, of combining said nitrogen with carbon from said petroleum coke and with the metal of said carbonate.

13. An improved briquet' for nitrogen fixation purposes, which comprises petroleum coke, finely divided iron and sodium carbonate, the -pores of said petroleum coke being substantially open and relatively free from said carbonate.

14; An improved briquet for nitrogen 'fixation purposes, which comprises finely divided petroleum coke, mixed with still more finely divided carbon obtained from the conversion of carbon monoxid to carbon dioxid, finely divided iron and sodium carbonate, the latter acting as the binder for said briquet.

' ieiaaei 15. An improved briquet for nitrogen fix-- ation purposes, which comprises substantially pure flocculent carbon as produced in" and deposited from gaseous material, finely divided catalytic material and a binderforming compound which acts both as a binder for said briquet and as a source of the metal which constitutes the base of the nitrogen compound to be formed, said carbon being present in such quantlty in and so intimately commingled .with'said binder forming compound that, when the latter is liquefied by heat, said carbon forms a' paste therewith. 16. An improved briquet for nitrogen flxation purposes, which comprises flocculent carbon, finely divided iron and sodium carbonate, the pores of said carbon being substantially open and relatively free from said 

